Thermochemical metal removal method and apparatus



1951 E. MEINCKE ETAL 2,536,201

THERMOCHEMICAL METAL REMOVAL METHOD AND APPARATUS 3 Sheets-Sheet 1 Filed April 19, 1946 lNVENTORg EDWARD ME/N x5 JOHN V/LLORES/ BY ATTO'RNEY 1 E. MEINCKE ETAL 2,536,201

THERMOCHEMICAL METAL REMOVAL METHOD AND APPARATUS 3 Sheets-Sheet 2 Filed April 19, 1946 vlfllilld'lllI!!!fllfllllllllllfllllffl W ll V/LLORES/ 107 6/ [/5 0g II INVENTORS RD ME/NCKE J0 BY ATTORNEY 1951 E. MEINCKE ETAL v 1 THERMOCl-IEMICAL METAL REMOVAL METHOD AND APPARATUS Filed April 19, 1946 3 Sheets-Sheet 3 ATTORNEY Patented Jan. 2, 1951 THERMOCHEMICAL METAL REMOVAL METHOD AND APPARATUS Edward Meincke, Summit, and John Villoresi, Lincoln Park, N. J., assignors to The Linde Air Products Company, a corporation of Ohio Application April 19, 1946, Serial No. 663,402

13 Claims.

1 This invention relates to a novel improved method of and apparatus for thermochemically removing metal from a metal body by applying thereto powdered adjuvant material in conjunction with a jet of oxygen and a preheating medium. While the novel method is applicable both to metals which resist and to metals which do not resist ordinary thermochemical metal removal procedures, it is especially advantageous for flame cutting or otherwise thermochemically removing metal from bodies of oxidation resistant metals and alloys such as high chromium steels, cast iron, copper, and numerous others. More particularly, the invention concerns such a novel method which is valuable for cutting narrow deep kerfs in metals bodies.

A recently developed novel process for thermochemically cutting, boring, flame machining, desurfacing, or otherwise thermochemically removing metal from metal bodies formerly considered resistant to thermochemical action involves applying to such a body a flowing stream of combustible adjuvant powder in conjunction with a metal-removing oxygen jet and an oxy-fuel gas preheating flame. Among the resistant metals which have been thus thermochemically worked successfully are high chromium steels having more than 5% chromium such as the well-known stainless steel of the 18% chromium-8% nickel type, tungsten steels, cast iron, copper and its alloys, aluminum, nickel, cobalt-chromium-tungsten alloys, and nickel base alloys containing molybdenum. More recently it has been found that the same procedure is also advantageous when applied to nonresistant ferrous metal bodies, such as carbon steels, because it greatly increases the rate of metal removal. This is reflected in either an increased speed of traverse over a metal body for a given quantity of metal removed, or an increase in the quantity of metal removed at a given speed of traverse. Furthermore, the use of combustible adjuvant powder in conjunction with the oxygen jet and preheating flame makes itpossible to start a cutting reaction instantly on a carbon steel or low alloy steel body, afterwhich the flow of adjuvant powder can be discontinued and the remainder of the cut completed in the usual way. Among the combustible adjuvant powders which have been used successfully are various forms of iron such as pure iron and mild steel, ferromanganese, iron-tin alloy, manganese, tin, lead, and mixtures of iron (e. g. mild steel) powder with ferromanganese, or manganese.

In the above-described process the adjuvant powder is usually aspirated into a metal-removing oxygen stream within a blowpipe nozzle, after which the powder-laden oxygen is discharged in a jet against a heated surface area On the body of metal from which metal is to be removed. To aspirate the powder into the oxygen stream, it is necessary to expand the flowing oxygen stream and reduce its velocity considerably with the result that the penetration of the oxygen jet into the metal body and the speed of traverse over the body are not completely satisfactory for cut ting a kerf. Furthermore, the relatively low velocity of the oxygen jet causes the kerf to be wider and rougher than is desirable.

Another procedure formerly followed in performing the new process involved aspirating a stream of powder into an oxygen jet on one side of the jet after discharge of the latter from the nozzle, while preheat flames burned on the opposite side of the jet. While such a procedure permits the oxygen to be discharged at high velocity, control of the rate of powder supply is insufliciently flexible and heating of the powder and the metal body by the flames is relatively ineflicient so that progress is slower than desirable and relatively rough wide kerfs are formed.

One of the principal objects of the present invention is to provide a novel improved method, overcoming the disadvantages discussed above, for thermochemically removing metal by applying an oxygen jet, a preheating medium, and combustible adjuvant powder to a metal body. Other objects are to provide such a method which is applicable tb both resistant and nonresistant metals; which is particularly advantageous for cutting metal bodies at high speed with improved penetration and the formation of narrow kerfs having smooth walls; and in which powdered adjuvant material is delivered to a zone of action in such a way as to permit flexible control of theh powder supply independently of the oxygen flow. I

Other objects are the provision of novel blowpipe apparatus which is suitable for performing the method of the invention; which efliciently preheats both the metal body being worked and the powdered adjuvant material, while discharging an oxygen jet at a high velocity; which has novel means for preventing the leakage of a combustible gas mixture into power passages; which has novel means for preventing the accumulation of powder in the threads of the blowpipe powder; which has removable and replaceable parts adapted to accommodate the blowpipe to a wide range of operating conditions; which is constructed to retard the accumulation of sintered powder on the nozzle; and which is so constructed that any adjuvant powder which sinters on the nozzle can be easily removed by the operator. Still other objects are to provide a novel arrangement of powder-and preheat passages in a cutting nozzle whereby powder consumption is reduced; and whereby sufliciently intense preheat is provided to prevent gouging or melting of the top edges of a kerf when a round bar is being cut.

In the drawings:

Fig. 1 is a. diagrammatic perspective view of one form of apparatus, including a blowpipe, suitable for performing the method of the invention;

Fig. 2 is a vertical midsectional view of the lower portion of the blowpipe shown in Fig. l, including the nozzle;

Fig. 3 is a sectional view taken along the line 3-3 of Fig. 2; g

Fig. 4 is a crosssectional view taken along the line 4-4 of Fi 3;

Fig. 5 is a lower end view of the blowpipe nozzle of Figs. 2 and 3;

Fig. 6 is a greatly enlarged vertical sectional view of a lower portion of the blowpipe nozzle shown in Figs. 2 to 5, inclusive;

Fig. '7 is a vertical mid-sectional view of the lower portion of another modified form of blow- P 1 Fig. 8 is a lower end view '01 the nozzle of Fig. '7

Fig. 9 is a vertical mid-sectiona1 view taken 1 along the line 9-9 of Fig. 10 showing the lower portion of a modified form of blowpipe;

Fig. 10 is a lower end view of the blowpipe shown in Fig. 9;

Fig. 11 is a vertical sectional view of a modified form of nozzle;

Fig. 12 is a lower end view of the nozzle of Fig. 11; I

Fig. 13 i a. lower end view of a nozzle similar to that of Fig. 11 but'modified to some extent;

Fig. 14 is a vertical mid-sectional view of the lower portion of still another modified form of blowpipe, taken along the line I l-I4 in Fig. 15;

Fig. 15 is a lower end view of the blowpipe of Fig. 14; and

Fig. 16 is an enlarged perspective view of an internal part of the blowpipe nozzle shown in Fig. 14.

In general, our improved method for thermochemically removing metal from a metal body comprises concurrently directing against the body a metal-removing oxygen jet, a preheating medium such as an oxy-fuel gas flame adjacent to the oxygen jet, and one or more streams of discrete particles of combustible adjuvant powder between the oxygen jet and the preheating medium. Whether the preheating medium is an oxy-fuel gas flame, an electric are, or som other high temperature heating medium, it is essential that it have suflicient heating intensity to heat at least the adjuvant powder to its oxygen ignition temperature. The adjuvant powder promptly ignites and burns in the oxygen jet, impinges against a zone on the metal body, and propagates its heat of combustion to the body, whereupon at least some of the constituents of the body in the zone of action ignite and burn in the oxygen jet forming a fluid slag consisting of molten metal mixed with fluid metal oxides. This slag is blown out of the Zone of action by the oxygen jet, leaving a cavity.

If metal is to be removed along a selected path we move the preheating medium, oxygen jet, and powder stream in unison across the surface relatively to the metal body in the proper direction to advance the zone of thermochemical action, while maintaining the preheating medium and at least a part of the powder stream in advance of the oxygen jet. It is apparent that this relative movement can be effected either by moving the preheating medium, oxygen jet, and powder stream in unison while holding the metal body stationary, or vice versa.

By following the above procedure, the adjuvant powder is preheated efliciently and the thermochemical reaction is confined to a small area, thereby assuring rapid progress and the removal of metal over a narrow area. Thi is especially advantageous for cutting because a narrow deep kerf having smooth cleanwalls is obtained. The advantages are still iurther accentuated when the preheating medium is arranged in a ring or envelope around the central oxygen jet, and the adjuvant powder is discharged in a rin or envelope between the oxygen jet and the preheat ring.

The method described briefly above can be performed successfully upon metals and alloys generally, including the metals and alloys mentioned previously herein in the introduction. However, nickel and copper must be preheated to about 1200 F. and 1500 F., respectively, before metal can be removed by our method. Furthermore, the combustible adjuvant or helping" powder can comprise any suitable combustible materials which assist the oxygen jet and preheating medium in removing metal thermochemically from metal bodies, including among others tne specific adjuvant materials mentioned previously herein in the introduction.

Although our novel method will be described more specifically hereinafter in connection with severing, it is apparent that the principles of the invention also apply to other thermochemical metal removing procedures such as boring, flame machining, and desurl'acing. Fig. 1 shows a metal billet l3 being cut thermochemically by a machine cutting blowpipe l5 so positioned as o direct an oxygen jet at a large angle against the billet surface, and carried by a motor-propelled carriage l'l traveling along a track 19. The blowpipe I5 is supplied with oxygen for both the cuttin jet and preheating flame, and with acetylene for the preheating flame, from suitable sources (not shown) through hoses 2| and 23, respectively. A needle valve 25 and a lever operated quick acting valve 33 control the flow of preheating oxygen and cutting oxygen, respectively, through the blowpipe; and the flow of preheating acetylene is controlled by a needle valve 21. A stream of carrier gas, such as compressed air, laden with powdered adjuvant material is supplied to the blowpipe through a third hose 29 in communication with a pneumatic powder dispenser 3| which receives carrier gas-through a valve-controlled conduit 32. A valve 35 near the rear end of the blowpipe controls the flow of powder laden carrier gas. The pneumatic powder dispenser 3l may be of any suitable construction such, for example, as the dispenser disclosed in Patent 2,327,337, granted August 24, 1943, to C. J. Burch and W. G. Edwards.

As shown in detail in Figs. 2 to 5, inclusive, the blowpipe [5 includes a lower body 31 secured at its upper end within a tubular handle I. and having a socket 45 in its lower end within which a cutting nozzle 4| is detachably secured by a coupling nut 4; bearing against a shoulder formed by the lower end of an annular boss 42 on the outside of a nozzle barrel 44. The cylindrical barrel 44'has front and rear ends, a central bore or passage 45 extending completely therethrough, and a plurality of longitudinal preheating gas passages 41, preferably three or more, arranged in a ring surrounding the central passage and converging forwardly toward the latter. The preheat passages 41 terminate at their front ends in a ring of outlets in the front end of the barrel 44, and at their rear ends on an annular shoulder 48 spaced from the rear end of the barrel and forming with the body 31 an annular gas distributing chamber 50. Gas tight seals 45 and 7 within the central bore 45 has a large diameter long flange 55 near its rear end which tapers slightly forwardly and mates snugly with a correspondingly tapered rear portion of the wall of the bore. From the flange 55 a reduced diameter portion 54 of the tube 53 extends forwardly in spaced relation to the wall of the bore to form an annular passage 51 around the tube for the passage of adjuvant powder. Oxygen passage 63 in tube 53 may be substantially cylindrical in shape, or may diverge to its outlet in a well known manner. The front end portion 55 of the tube 53 tapers slightly forwardly and projects a short distance beyond the end of the barrel 44 so that any powder which sinters will accumulate outside of the barrel where it can be easily brushed off. The front of the tube 53 is spaced from the wall of thebore 45 by a plurality of radial projections 6| integral with the tube a short distance from the front end of the latter and located within the bore in spaced relation to the end of the barrel 44 so as to provide an annular space 62 for discharging an annular stream of powder from the nozzle. A plurality of longitudinal ducts between the projections 6|! afford passage for the powder. It is apparent that the projections 50 need not be integral with the tube but would function satisfactorily no matter how they are arranged between the tube and the barrel. Powder is supplied to the annular chamber 51 by a plurality of circumferentially arranged lateral powder inlet ports 65 in the barrel 44 extending from a rear portion of the annular chamber 51 just in front of the flange 55 diagonally rearwardly between preheat passages 41 to the outside of the barrel, where they receive powder laden gas from an annular distributing chamber 55 formed between the barrel and an annular recess in the wall of the socket 40.

In order to insure that no combustible gas mixture will leak into the powder passages of the blowpipe an auxiliary seal below-the seal 5| is provided by mounting an annular gasket 64 of rubber or like compressible and resilient material on an annular shoulder 58 located on the outside of the barrel 44 between the rearmost conical seat and the rear ends of the passages 55. When the nut 43 is tightened the gasket 64 is pressed against the rear wall of the chamber 55 to form a tight seal. A second similar gasket is mounted in an annular groove in the annular boss 42 in such a way as to press against the wall of the socket the jet and to be at last 6 below the real ends of the H v as t, thus preventing particles of powder from dropping into the threads of the nut 43 and body 31.

When operating the blowpipe Ii, a part of the gaseous oxygen from the hose 2| is mixed within the blowpipe with the fuel gas, such as acetylene, from the hose 23 in a conventional manner to form a combustible gas mixture for preheating. This mixture flows through a tube OI to a passage 1| in the body 31 and into the annular recess 50 which distributes the mixture to the preheat gas passages 41. when the valve is open the rest of the oxygen from the hose 2| passes through a tube 13 to a passage 15 in the body 31, and thence into the cutting oxygen passage 63. Powder-lader gas from the supply hose 2! passes through a third tube 11 to a bore II in the body 31 and into theannular distributing chamber 68. which distributes the powder to all of the inlet ports 65 in the nozzle. Thence the powder laden gas flows through the longitudinal annular passages 51 and leaves the blowpipe in an annular stream which, due to thetaper on the end of the tube 53, expands inwardly toward and envelopesthe oxygen jet in such a way as to merge with at least the peripheral portion of partially transported thereby.

When cutting a kerf by our novel improved method with a blowpipe such as described above, the front end of the nozzle 4| is positioned far enough above the surface of the body l3 to insure ignition of the powder'particles, usually at least five eighths of an inch but not more than live inches. The preheat gas streams from the several passages 41 are ignited and burn as intensely hot flames 83 which preheat both the annular combustible adjuvant powder stream 85 leaving the passage 51, and an area on the surface of the metal body IS. The adjuvant powder in the stream 85 quickly reaches its ignition temperature and burns in the oxygen from the central oxygen jet 81, liberating a large quantity of heat which is propagated promptly to the heated surface area of the metal body upon impingement of the burning powder particles thereon. In this way a small portion of metal on the surface of the body I3 is heated quickly to its ignition temperature-and starts to burn in the excess oxygen in the jet 81, thus liberating additional heat and forming a fluid mixture of metal oxide and molten metal which is blown out of the zone of reaction by the oxygen jet and exposes a. fresh metal surface to the action of oxygen and powder.

As shown in Figs. 1 and 2, the blowpipe nozzle 4| is held at a large angle to the surface of the body It, such as about with the result that the oxygen jet 81 penetrates through the body and forms a deep narrow kerf 89. When starting the cut, the nozzle 4| is positioned at an edge of the body with oxygen, powder, and preheat gases flowing. At the instant that the cutting action starts, movement of the carriage |1 along the track I9 is initiated to move the blowpipe nozzle 4| across the body 13 parallel to its surface in the direction of the arrows in Figs.

. 1 and 2, thus extending the kerf 89 progressively along the selected path. Flying starts also can be made by positioning the blowpipe l5 away from the edge of the body l3, and then starting the carriage I! at normal cutting speed while concurrently discharging preheating flames, cutting oxygen, and adjuvant powder from the blowpipe. In this way, the cut starts at the instant when the cutting oxygen jet and adjuvant powder stream impinge against the metal, without requiring a halt in the advance of the blowpipe for preheating. Ordinarily the kerf 89 is carried completely through the body to sever the two adjoining portions but, if desired, the blowpipe l can be moved along the selected path at a rate sufliciently rapid that the oxygen jet 81 penetrates only part way through the body and forms a deep nick.

Observation of the cutting action of the oxygen jet 81, the preheating flames 83, and the powder stream 85 has shown that the powder particles are heated to ignition temperature by the preheat flames and the burning particles on the leading side of the powder envelope strike the body to be cut and are burned completely, liberating enough heat so that a part of the body is melted and the oxygen jet can react with the metal, thus liberating more heat. A small proportion of the powder on the leading side of the oxygen jet is continually deposited in a molten condition on the top surface of the bod l3, as shown at 9| in Fig. 2. When the cutting oxygen jet 81 reaches this molten adjuvant material 9|, the latter immediately and completely burns and heats the base metal to its oxygen ignition temperature. Resistant metals apparently must be melted or near the melting temperature before they will ignite, but readil -oxidizable ferrous metals ignite below the melting point. The major proportion of the powder is carried down into the kerf by the oxygen jet, where it burns to provide additional heat within the zone where it is most beneficial, thus permitting formation of a deep kerf with but little lag.

When the adjuvant powder burns, the oxide product unites with the slag, consisting of oxides of the base metal and molten base metal, to form a highly fluid complex slag which is blown from the reaction zone by the oxygen. Using the described procedure a drop out can be obtained on four inch thick 18% cr-8% Ni stainless steel when carrying a A; to ,5; inch lag, indicating that the necessary heat is being supplied b the burning powder to maintain the oxidation reaction at a distance of fourinches below the nozzle tip.

When the passages of the blowpipe nozzle 4| are so constructed and arranged that the powder-laden gas stream 85 impinges against the outer periphery of the oxygen jet 81, and the preheat flames 83 converge forwardly toward the oxygen stream, as shown in Fig. 2, the best cutting conditions exist. Intimate contact of the powder with the oxygen is obtained, while the diameter of the oxygen jet is maintained small enough to produce a narrowkerf. Furthermore, the converging preheat flames preheat most of the adjuvant powder to its ignition temperature before it reaches the surface of the metal body. Without such an arrangement of passages, it is necessary to impair the efiiciency of the procedure and increase the kerf width by raising the nozzle to a considerable height above the surface of the metal body to insure ignition of the metal powder before it reaches the surface.

With the described cutting procedure and apparatus it is possible to cut stainless steel bodies of the 18% Cr-8% Ni type at high speeds approaching the cutting speed ordinarily obtained with carbon steels. After the oxygen jet has initially penetrated the resistant metal body being cut, the cutting speed can be increased as The following table contains representative data concerning the cutting of 18% Cr-8% Ni type stainless steel bodies by the method described above, using an oxy-acetylene cutting blowpipe of the type shown in Figs. 2 to 5, inclusive, and steel adjuvant powder. Results are not exactly comparableto one another because various nozzle sizes were used.

Powder Ker! 01 Pressure, Spee Thickness, Inches 022% mJmuL wligtlh,

Also using the method of the invention, two inch thick slabs of a nickel-base alloy containing molybdenum, chromium, iron, and tungsten have been successfully flame-cut at a rate of four inches per minute using adjuvant powder comprising 80% steel and 20% ferromanganese.

When the proportion of powder to oxygen and the oxygen velocity are properly controlled the out suriace of an oxidation resistant metal body, such as a high chromium stainless steel containing more than 5% chromium, is substantially smooth and plane, and has a slightly sandy feel. After the metal has cooled the scale and slag pop off spontaneously, and the cut surface has a bright and shiny metallic appearance, a slightly sandy feel, and is substantially as oxidation resistant as the parent metal. For a high chromium stainless steel of the 18% Cr-8% Ni variety, this type of surface has been obtained by using about 35 cu. ft./hr. of oxygen to l 1b./hr. of an adjuvant powder composed 80% of low-carbon steel powder intimately mixed with 20% of ferromanganese powder.

An advantage of the two-piece nozzle construction of Figs. 2 to 5 is that the tube 53 can be easily removed from the central passage 45 of the nozzle 4| for repair, or for replacement with a tube having different proportions if different characteristics of the cutting oxygen jet and powder streams are desired. A still more important advantage of the two-piece nozzle construction, however, is that the adjuvant powder passage can be completely lined with an abrasion resistant material which will prevent the relatively soft metal of the nozzle, which is usually copper, from being eroded rapidly by the abrasive adjuvant powder. Bushings and sleeves of abrasion resistant materials can be used. A more desirable way for forming such a lining, however, is to plate both the wall of the central bore 45 and the outside wall of the tube 53 with layers 92 and 94 of chromium before the tube 53 is inserted into the bore, as shown in Fig. 6. Other abrasion resistant lining materials can be applied in the same or in different ways while the parts of the nozzle are separated. Without this construction it would be almost impossible to plate the walls of such small powder passages.

In the alternative blowpipe construction hown in Figs. 7 and 8 the end of the oxygen tube 93 is recessed slightly from the front end of the nozzle 95 to form a recess 88 for reducing the sintering of powdered adjuvant material on the nozzle without substantially reducing the oxygen velocity before discharge. Additionally, the front end of the oxygen tube 93 is centered within the nozzle by narrow fins 96 on the tube, thereby permitting the discharge of powder as separate streams which merge before or just after discharge to form an annular stream. Another diiference over the blowpipe of Figs. 2 to 5 is the provision of three conical seats 91, 98, and 99 on the rear end of the nozzle which separate the oxygen passages from the preheat gas passages, the preheat gas passages from the powder passages, and the powder passage from the atmosphere. Also the rear end of the tube 93 has an annular flange which abuts against the rear end of the nozzle 95, instead of the tapered flt construction of Figs. 2 to 5.

In the modified form of blowpipe construction shown in Figs. 9 and 10, a conventional cutting nozzle I carried in a body IOI has a central cutting oxygen passage I02 and a surrounding ring of preheating passages I03. Adjuvant powder is introduced between the central oxygen jet and the preheat flame ring by-a port I04 having a single outlet arranged between the outlet of the central passage I02 and the ring of outlets of the preheat passages I03, and extending diagonally rearwardly between two of the preheat passages to its orifice in the outside wall of the nozzle. The port I04 is supplied with powder by a tube I05 secured to the nozzle I00, as by brazing, and opening at its front end into the port I04.

The nozzle shown in Figs. 9 and 10 is satisfactory for machine flame cutting along a straight'line, where it is always possible to maintain the port I04 ahead of the oxygen passage I 02. However, when a crooked cut is to be made, this nozzle is not as effective as the nozzles of Figs. 2 to 8, inclusive, because in the latter the powder surrounds the oxygen jet so that powder will always lead the jet no matter how the nozzle is turned.

The nozzle I01 shown in Figs. 11 and 12 can be used in a blowpipe body of the type shown in Fig. 7. This nozzle comprises a unitary body of copper or the like having a longitudinal central oxygen passage I09, and a plurality of longitudinal preheat passages II I arranged in a ring surrounding the oxygen passage as in conventional cutting nozzles. However, the nozzle I01 also has a plurality of longitudinal straight adjuvant powder passages II3 having inlets in the rear end of the nozzle arranged on a ring of larger diameter than the ring of preheat passages II I, and outlets in the front end of the nozzle arranged on a ring of smaller diameter than the ring of preheat passages, between the latter and the outlet of the oxygen passage I09. It is apparent, therefore, that the powder passages II3 extend diagonally rearwardly from their outlets to their inlets between the preheat passages III. This unitary nozzle construction of Fig. 11 is satisfactory for cutting metal bodies by the method of the invention but has a short life because the flowing adjuvant powder tends to erode the walls of the passages I I3.

As shown in Fig. 13, instead of constructing the nozzle of Figs. 11 and 12 with a plurality of adjuvant powder passages II3, a single powder pasa single stream of powder ahead of the oxygen jet, as with the nozzle construction of Fig. 9.

The modification shown in Figs. 14 to 16 is especially designed for cutting and starting cuts on round bars. A standard machine cutting .blowpipe head I carries a nozzle I21 having a central longitudinal passage I29 within which is disposed a removable tube I3I having a cutting oxygen passage I33, substantially in the manner described in connection with Figs. 2 to 5. Near to but spaced from the lower end of tube I3I is an annular tube spacing plug or flange I35 which has three longitudinal grooves or ducts I31 therethrough grouped together and entirely located within a semicircle at one side of the flange for carrying adjuvant powder from the annular space I39 above the flange to the annular space I below the flange, whereby the major portion 01' the powder leaving the nozzle is distributed on one side of the central cutting oxygen jet.

Instead of introducing the adjuvant powder into the annular space I39 from the blowpipe head I25, the nozzle I21 has an upwardly and outwardly inclined bore I43 extending from the central passage I29 to the outside of the nozzle some distance above the flange I35 on the opposite side of the nozzle from the three ducts or grooves I31. A supply tube I45 for powder is secured in the bore I43, as by welding, and can be connected to a powder dispenser of the type shown in Fig. 1. By locating the powder inlet bore I 43 and the ducts I 31 on opposite sides of the tube I3I, a continuous flow of powder is obtained without clogging above the flange I35. Clogging may occur if the powder is introduced to passage I39 on the same side as the ducts I31.

Heating flames are provided by the combustion of an oxy-fuel gas mixture leaving a plurality of longitudinal passages I41 and I49 'in the nozzle which are supplied with gas from a sages I49 being grouped close together in a 144.

arc on the same side of the oxygen passage I33 as the powder ducts I31, and the single outlet sage II5 having an outlet between the oxygen of passage I41 being located on the opposite side of the oxygen passage I33.

In using the blowpipe of Figs. 14 to 16, the nozzle I21 is advanced in the direction of the desired cut with the flames from preheat passages I49 and the powder from ducts I31 leading the cutting oxygen jet from passage I29, and with the heating flame from the single passage I41 trailing the cutting oxygen jet, as indicated by the arrow CD in Fig. 15. Approximately of the heat comes from the grouped passages I49 which precede the oxygen jet. The described arrangement of passages is such that satisfactory instantaneous cutting starts can be made on cold round carbon steel bars with a minimum of powder consumption. Furthermore, the described arrangementof passages has been found to prevent gouging through the first half of a round bar, and to prevent melting of the top edges of a kerf when continuing a out after the flow of adjuvant powder has been discontinued. The trailing flame from passage I 41 is necessary for preventing an excessively large lag in the kerf by maintaining the slag hot enough to flow smoothly and continuously through the kerf.

Other advantages of the blowpipe of Figs. 14 to 1 are the facts that the nozzle I21 can be used with a standard blowpipe head, and that there is no possibility of damaging the seats in the nozzle or blowpipe head or galling the threads of the nozzle coupl ng nut I53 and the cooperating threadsinhead I25.

The invention has been described in detail above by way of illustration only, and changes in the construction and relative arrangement of parts of the apparatus, and in the steps of the method can be made within the spirit of the invention. Therefore, it is apparent that the principles of the invention are not limited to the specific procedures and apparatus described above, but are of a broader scope as defined in the appended claims.

This appl cation is a continuation-in-part of our application Serial No. 573,192, filed January 17, 1945, now abandoned.

We claim:

1. A blowpipe nozzle for thermochemically removing metal, having a first longitudinal passage provided with a first outlet in an end surface of said nozzle for discharginga metal-removing oxygen jet, a plurality of second longitudinal passages having second outlet means in said surface arranged in a ring surrounding and adiacent to said first outlet for d scharging combustible preheat gas, and at least one third passage having a third outlet in said surface between said first outlet and said second outlet means for discharging adjuvant powder, said third passage extending rearwardy in said nozzle from said third outlet transversely between two of said second passages to the outside of said nozzle.

2. A blowpipe nozzle according to claim 1 wherein said first out et and said third out et are located substantially at the discharge end of said nozzle but are recessed slightly therefrom sulficiently to reduce sintering of powder on said nozzle without substantia ly reducing the velocity of said oxygen jet prior to discharge thereof from said nozzle.

3. A blowpipe nozzle according to claim 1 wherein said first outletof said first passage is located downstream of said outlets of said second and third passages, whereby any sintered adjuvant powder accumulates on said nozzle where it is readily accessible and can be easily removed.

4. Blowpipe apparatus for thermcchemically removing metal comprising a nozzle having a first longitudinal passa 'e provided with a first outlet in a surface of said nozzle for dischar ing a metal-removing oxygen jet, a plura ity of second lon itud nal passages having outlet means in said surface arranged in a ring surrounding and adjacent to said first outlet for discharging combustible preheat gas, third lon itudinal passage means having outlet means arranged in a ring between said first outlet and said second outet means for d scharging combustible adjuvant powder, said third passage means including an annular powder chamber surrounding said first passage and extending forwardly from a locality intermediate the ends of said nozzle, and a powder inlet port establishing communication between said annular chamber and the outsde of said nozzle, said port extending transversely between two of said second passages; said blowpipe apparatus also havin passages for supplying oxygen, combustibe preheat gas, and adjuvant powder to said first passage, said second passages, and said port, respectively.

5. A blowpipe nozzle comprising a barrel having front and rear ends, said barrel having a first longitudinal passage therethrough provided with a wall, and a plurality of longitudinal preheat gas passages arranged in a ring around said first passage and having outlet means for discharging through said front end; an oxygen conducting tube within said first passage spaced from said wall to form an annular powder conduit around said tube, a rear portion of said tube gas-tightly engaging said wall, said tube having a front end terminating substantially at said front end of said barrel; centering means between said wall and said tube near the front of the latter, said centering means defining a plurality of powder ducts around said tube; and said barrel having at least one powder inlet port establishing communication between said annular powder conduit and the outside of said body, said port extending transversely between two of said preheat gas passages.

6. A blowpipe nozzle comprising a barrel having front and rear ends, said barrel having a longitudinal first passage therethrough provided with a wall, and longitudinal preheat gas passage means having outlet means arranged as a ring in said front end around said first passage; an oxygen conducting tube within said first passage spaced from said wall to form an annular powder conduit around said tube, said tube having a front end projecting beyond the front end of said barrel sufficiently to cause any sintered powder to accumulate on said nozzle in a readily accessible position from which it can be easily removed; and centering means between said wall and said tube near the front of the latter, said centering means defining a plurality of powder ducts and said centering means being recessed within said first passage a short distance such that streams of powder leaving said powder ducts again merge in said annular conduit and are discharged therefrom in an annular stream.

'7. Blowpipe apparatus for thermochemically removing metal having a nozzle provided with a front end and a side wall, a first longitudinal passage means in said nozzle having a first outlet for discharging a metal-removing oxygen jet through said front end, a second longitudinal passage means in said nozzle having a second outlet adjacent to said first outlet for discharging combustiblepreheat gas through said front end, a conduit means in said nozzle having a third outlet between said first and second outlets for discharging adjuvant powder through said front end, said conduit means extending rearwardly from said third outlet and having an entrance in said side wall, and a tube secured to said nozzle in communication with said entrance and projecting from said side wall for supplying adjuvant powder to said conduit means.

8. A blowpipe nozzle having a central longitudinal passage means for discharging an oxygen jet, an annular passage means for powder surrounding said central passage means, a powder met to said annular passage means, a plug in said annular passage means said plug having longitudinal duct means therethrough entirely located within a semicircle on one side of said central passage means for guiding such powder to one side thereof for discharge principally on 13 tudinal passage means for discharging an oxygen let, an annular passage means for powder surrounding said central passage means, a plug in said annular passage means-said plug having longitudinal duct means therethrough entirely located within a semicircle on one side of said central passage means for guiding such powder to one side of said annular passage means for discharge principally on one side of said oxygen Jet, and a powder inlet to said annular passage means only on the side thereof opposite said firstnamed side.

10. In a method for progressively thermochemically removing metal from a metal body by the conjoint action of a metal-removing oxygen jet, a preheating flame, and a stream of burning combustible metallic adjuvant powder advancing along and impin g against the surface thereof, the improvement which comprises: separately but concurrently discharging into free space adjacent the surface of said body and thence against said body a central metal-removing oxygen jet; a first ring comprising one or more air streams laden with such adiuvant powder surrounding and alongside said oxygen Jet; and a second ring comprising a preheating combustible gas mixture unburdened with powder surrounding and alongside said first ring, said mixture burning to form a preheating flame for heating such powder rapidly to the ignition temperature thereof and for heating said body.

11. In a method in accordance with claim 10, said preheating combustible gas mixture converging toward'said first ring of powder-laden gas and said central .oxygen jet.

12. Blowpipe apparatus for thermochemically removing'metal comprising a body; a nozzle secured at one end thereof to said body, said nozzle having a first longitudinal passage provided with a first outlet in the surface of said nozzle at the opposite end thereof for discharging a metal-removing oxygen jet, a plurality of second longitudinal passages having second outlet means in said surface arranged on a ring adjacent to and surrounding said first outlet for discharging combustible preheat gas, and at least one third passage having third outlet means in said surface between said first and second outlet means for discharging adjuvant powder, said third passage extending rearwardly in said nozzle from said third outlet means transversely between two of said second passages to the outside of said nozzle; said body having passages therein for supplying oxygen and combustible preheat gas to said first and second es, respectively; II

and said blowpipe apparatus also comprising passage means for supplying adiuvant powder to said third e means.

13.11 blowpipe male for t mnochc ically 14 removing metal comprising a unitary body of metal having integrally formed therein a first longitudinal passage provided with a first outlet in an end surface of said nozzle for discharging a metal-removing oxygen Jet, a plurality of sec nozzle.

EDWARD MEINCKE. JOHN VILLORESI.

REFERENCES CITED The following references are of record in. th file of this patent:

UNITED STATES PATENTS Number Name Date 874,666 Gauthier et a1. Dec. 24, 1907 968,350 Harrison Aug. 23, 1910 1,178,551 Stolle et a1 Apr. 11, 1916 1,247,791 Carlson Nov. 27, 1917 1,328,329 Johnson Jan. 20, 1920 1,412,656 Jenkins Apr. 11, 1922 1,494,003 Malcher May 13, 1924 1,586,010 Shelburne May 25, 1926 1,606,013 Wulif Nov. 9, 1926 1,624,377 Walker Apr. 12, 1927 1,808,968 Plumley June 9, 1931 1,840,195 Hasse Jan. 5, 1932 1,840,196 Hasse Jan. 5, 1932 1,926,438 Fausek et a1 Sept. 12, 1933 2,110,634 Rehmann Mar. 8, 1938 2,176,813 Hammon Oct. 17, 1939 2,181,095 Ness Nov. 21, 1939 2,210,402 Gaines Aug. 6, 1940 2,224,171 Van Triest Dec. 10, 1940 2,286,192 Aitchison et a1 June 16, 1942 2,317,936 Nicholson et al Apr. 27, 1943 2,365,411 Jacobsson Dec. 19, 1944 2,368,716 Marra Feb. 6, 1945 2,444,900 Meincke et al. July 6, 1948 2,451,422 Wagner Oct. 12, 1948 2,465,978 Meincke Mar. 29, 1949 2,470,999 Meincke May 24, 1949 FOREIGN PA'IENTB Number Country Date 641/26 Australia Ebb. 19, 1926 426,990 Germany Dec. 31, 1926 549,781 Germany May 2, 1932 

10. IN A METHOD FOR PROGRESSIVELY THERMOCHEMICALLY REMOVING METAL FROM A METAL BODY BY THE CONJOINT ACTION OF A METAL-REMOVING OXYGEN JET, A PREHEATING FLAME, AND A STREAM OF BURNING COMBUSTIBLE METALLIC ADJUVANT POWDER ADVANCING ALONG AND IMPINGING AGAINST THE SURFACE THEREOF, THE IMPROVEMENT WHICH COMPRISES: SEPARATELY BUT CONCURRENTLY DISCHARGING INTO FREE SPACE ADJACENT THE SURFACE OF SAID BODY AND THENCE AGAINST SAID BODY A CENTRAL METAL-REMOVING OXYGEN JET; A FIRST RING COMPRISING ONE OR MORE AIR STREAMS LADEN WITH SUCH ADJUVANT POWDER SURROUNDING AND ALONGSIDE SAID OXYGEN JET; AND A SECOND RING COMPRISING A PREHEATING COMBUSTIBLE GAS MIXTURE UNBURDENED WITH POWDER SURROUNDING AND ALONGSIDE SAID FIRST RING, SAID MIXTURE BURNING TO FORM A PREHEATING FLAME FOR HEATING SUCH POWDER RAPIDLY TO THE IGNITION TEMPERATURE THEREOF AND FOR HEATING SAID BODY. 